Recesses along the posterior margin of the infrapatellar (Hoffa’s) fat pad: prevalence and morphology on routine MR imaging of the knee

The objective is to evaluate the prevalence and morphology of recesses along the posterior margin of the infrapatellar fat pad on routine MR imaging of the knee. MR images of 213 knees in 204 consecutive individuals were evaluated with regard to the prevalence and morphology of recesses (a suprahoffatic recess close to the inferior border of the patella and the previously described infrahoffatic recess anterior to the inferior portion of the infrapatellar plica). The recesses were analyzed with regard to synovial effusion and the condition of the anterior cruciate ligament (ACL). Anatomic dissection was made in 29 knees in 16 cadavers to verify the presence of the suprahoffatic recess. The infrahoffatic recess was present in 45% of the knees and mostly linear in shape (44%). The suprahoffatic recess was detected in 71% of the knees (45% in cadavers). Very weak to moderate positive correlation was found between the synovial effusion or the condition of the ACL and the presence and dimensions of the recesses. An awareness of the recesses in the infrapatellar fat pad is important in order to distinguish between pathology and anatomic variants on routine MR imaging of the knee.     

The “sickle-sign” in bone scintigraphy

A side-effect of an intensive cytotoxic treatment on bone scanning will be reported: the socalled sickle sign, a diffuse activity arlund the calvarium seen only in patients at cytotoxic therapy. The differentiation between this harmless side-effect and abnormalities caused by the cancer could be done in our patients by a vertex view. All patients with skull metastases or meningeal carcinosis and this sign in the frontal and lateral view had an inhomogenous uptake in the vertex view. This view should therefore be added to the standard views in all patients with the sickle sign.     

The Chiari II malformation: Part IV. The hindbrain deformity

Summary Computed tomography successfully delineates the multiple components of the Chiari II malformation at the craniocervical junction, the hindbrain, and the cervical spinal cord. These include wide foramen magnum and upper cervical spinal canal; incomplete fusions of the posterior arches of C1 and lower cervical vertebrae; cascading protrusions of vermis, fourth ventricle, medulla, and cervical cord into the spinal canal; cervicomedullary kinking; anterior displacement and sequential sagittal compression of each protrusion by the protrusions posterior to it; compression of all protrusions by the posterior lip of foramen magnum and the posterior arch of C1; and associated cervical hydromyelia, cervical diastematomyelia, and cervical arachnoid cysts.Presented in part at the CT '82, International Computer Tomography Symposium, Seefeld/Tirol, Austria, 28–30 January 1982; and presented in nearly complete form at the 10th Annual Meeting of the International Society for Paediatric Neurosurgery, Philadelphia, Pennsylvania, USA, 12–15 September 1982     

Diagnosis of neuroendocrine tumours by retrospective image fusion: is there a benefit?

This study evaluated the use of image fusion in the preoperative staging of neuroendocrine tumors (NET) of the pancreas and the gastrointestinal tract (GIT). Thirty-eight patients suffering from a metastasized NET with location of the primary in the pancreas (n=15) or the GIT (n=23) were examined by somatostatin receptor scintigraphy (SRS) and computed tomography (CT). Consecutive image registration and fusion were performed using custom-built software integrated in AVS/Express (Advanced Visual Systems, Waltham, MA, USA). Registration was performed by a voxel-based algorithm based on normalized mutual information. Image fusion was feasible in 36/38 patients. A total of 87 foci were assigned to anatomical regions (e.g. gut, pancreas, liver, lymph node or others) by two independent observers in both SRS and SRS/CT fusion images. The assignments used a binary ranking system (1=definite, 0=not definite). These results were then retrospectively compared to the classification of the foci, based on postoperative histology or clinical follow-up. Imaging by SRS allowed a definite anatomical assignment in 57% (50/87) and 61% (53/87) of all lesions in the case of observers A and B, respectively. Image fusion improved the topographic assignment to 91% (79/87) and to 93% (81/87). The number classified as definite by both observers increased from 54% (47/87) to 86% (77/87). The increase in definite assignments was highly significant for both observers (P<0.0001 for each). In the case of foci classified as liver metastases, image fusion allowed improved assignment to the corresponding liver segment from 45% (18/40) to 98% (39/40) and from 58% (23/40) to 100% (40/40) by observers A and B, respectively. Furthermore, the improved assignment of foci classified as lesions by image fusion was relevant for therapy in 7/36 patients (19%). Therefore, the image fusion technique presented herein appears to be a very useful method for clinical routine.     

SLAP lesions of the glenoid labrum diagnosed with MR imaging

Tears of the superior portion of the glenoid labrum in patients without shoulder instability have recently been described. These tears, which include the anchor of the biceps tendon to the labrum, have been labeled SLAP lesions (superior /abrum anterior to posterior). This study was performed to determine the magnetic resonance (MR) findings in patients with SLAP lesions. Retrospective review of the shoulder arthroscopy reports on patients who underwent MR imaging using a 1.5-T unit and subsequent arthroscopy by a single surgeon identified six patients with SLAP lesions (average age 36 years, range 17–65 years). MR images demonstrated atypical morphology indicative of tear in the superior portion of the labrum in four of the six patients, but only one tear had been identified preoperatively. Radiologists interpreting MR images of the shoulder should be aware of the MR findings of SLAP lesions as these tears can be a significant cause of patient disability and are difficult to diagnose clinically.     

Infratentorial brain maturation: a comparison of MRI at 0.5 and 1.5T

Our purpose was to establish parameters for normal infratentorial brain maturation at 0.5 and 1.5T and to evaluate the field strength criteria for the assessment of infratentorial brain maturation with MRI. We examined 27 children with normal psychomotor development (3 days to 24 months) with a 1.5T system and 22 (4 days to 29 months) with a 0.5T system; standard T2-weighted spin-echo sequences (TR/TE 2500/90 ms at 1.5T and TR/TE 2200/90 ms at 0.5T) were obtained. The signal intensity of infratentorial anatomical structures compared to their surroundings was classified as high, isointense or low by three neuroradiologists. For anatomical structures with age-related contrast changes, the time of these changes was determined statistically for the 0.5T and 1.5T system independently. The delineation of the structures without age-related contrast changes at the two field strengths was compared using a ² test. Age-related contrast changed were found in the same anatomical structures (marker sites) at 0.5 and 1.5T. Generally, these changes were apparent in larger structures (pons, middle cerebellar peduncles, medulla, cerebellar folia, red nuclei, cerebral peduncles), with only slight field-strength-dependent differences in the time of the contrast changes. Contrast changes from high to isointense signal were observed slightly earlier at 0.5T and changes from isointense to low signal slightly later at 0.5T. The delineation of the smaller anatomical structures was significantly better at 1.5T but these structures did not show age-related contrast changes. The differences in the assessment of infratentorial brain maturation between 0.5 and 1.5T can be attributed to a lower signal-to-noise ratio at lower magnetic field strengths. These differences do not complicate temporal classification of the stage of infratentorial brain maturation using the same marker sites and the same temporal criteria at 0.5 or 1.5T. However, higher field strengths are preferable for the assessment of smaller structures with physiological signal differences; this may imply better detection of small lesions at higher field strengths.     

The frontal intersinus septal air cell: a new hypothesis of its origin

BACKGROUND AND PURPOSE: Air cells are often seen within the frontal intersinus septum. These cells have traditionally been thought to arise from displaced ethmoid cells from the frontal recess. This study explores the possibility that such cells may actually be diverticula from the frontal sinuses themselves and not of a direct ethmoid origin.MATERIALS AND METHODS: A prospective study of 200 consecutive CT scans in the coronal and axial planes was performed on patients without a history of recent trauma. The images were interpreted independently by a radiologist and an otolaryngologist. The CT studies were evaluated for the presence of a central intersinus septal air cell. If such a cell was identified, it was further classified as either being completely isolated from both frontal sinuses by a bony rim or as a communicating diverticulum from one of the frontal sinuses. If a central cell was present, it was also assessed for how much of the height of the intersinus septum it involved (lower one-half or full height).RESULTS: There was a complete concordance of the results between the 2 observers. An intersinus septal air cell was seen in 61 (30.5%) of the 200 cases, and 85.3% of these cells were clearly seen to communicate anteromedially with either one of the frontal sinuses or both frontal sinuses (3 cases). In 9 (4.5%) of the 200 cases, the central cell had no demonstrable connection to either frontal sinus. Of the 61 cases with a central cell, 55 (90.16%) of the cells occupied the full height of the septum, and 6 (9.84%) only involved the lower half of the septum.CONCLUSION: Contrary to the present convention that frontal intersinus septal cells originate as displaced ethmoid cells from the frontal recess, we found that most such cells are actually diverticula from the frontal sinuses themselves.

The development of the frontal sinus from the anterior ethmoid labyrinth allows for the presence of extramural ethmoid cells both around and within the frontal sinus proper. These cells, which communicate with the frontal recess, include supraorbital, infrafrontal, and intersinus septal cells. Such cells were identified by anatomic dissection studies in the first part of the 20th century and were subsequently detailed by radiographic imaging in living patients.^1–3The belief that there was a common embryogenesis of the frontal sinus and associated cells by evagination and pneumatization from the frontal recess have resulted in a generally accepted unifying hypothesis of their formation. However, our study challenges the concept that the intersinus septal cell is uniformly of an ethmoid derivation. Rather, we suggest that such a cell may most often represent a diverticulum from the frontal sinus itself.     

Neuropsychological correlates of brain atrophy in Huntington's disease: a magnetic resonance imaging study

Summary Magnetic resonance imaging and a comprehensive cognitive evaluation were carried out in a series of 29 patients with mild to moderate Huntington's disease (HD). A factor analysis of the neuropsychological test scores provided three factors: a memory/speed-of-processing factor, a frontal factor, and a response inhibition factor. The memory/speed factor correlated significantly with measures of caudate atrophy, frontal atrophy, and atrophy of the left (but not the right) sylvian cistern. There were no significant correlations between the frontal or response inhibition factors and measures of cortical or subcortical brain atrophy. Our findings confirm that subcortical atrophy is significantly correlated with specific cognitive deficits in HD, and demonstrate that cortical atrophy also has important association with the cognitive deficits of patients with HD.     

Multiple segmental agenesis of the cerebral arteries: case report

A case of multiple segmental agenesis of the cerebral arteries is presented. Cerebral angiography demonstrated bilateral socalled carotid rete mirabile, a similar rete of the right vertebral artery and intradural duplication of the left vertebral artery. These abnormalities are thought to be caused by multiple segmental agenesis of the cerebral arteries as they penetrate the dura mater, the embryological and anatomical significance of these findings is discussed.     

Fogging on T2-weighted MR after acute ischaemic stroke: how often might this occur and what are the implications?

Fogging is the temporary loss of visibility of an infarct on CT which occurs in the subacute phase at about 2 weeks after stroke. It occurs in up to 40% of medium to large infarcts on CT. It is unclear whether or how often fogging occurs on T2-weighted MR, but if it does occur, it can cause underestimation of true infarct size. This study examined the possible frequency and time scale of fogging on T2-weighted MR. We conducted a blinded, independent review of prospectively collected MR scans from patients with symptoms of cortical ischaemic stroke, scanned sequentially up to 7 weeks after stroke. On each scan maximum infarct area was measured, and the infarct extent and swelling were coded on a validated scale. Fogging was suggested by reduced infarct extent between initial and subsequent scans. In 30 patients (with 74 scans) there was some apparent fogging in 50% of patients between 6 and 36 days (median 10 days) after stroke. Reduction in infarct extent on T2-weighted MR which may be attributed to fogging occurs in a significant proportion of patients with cortical infarcts. This may lead to an underestimation of true final infarct extent. This suggests that true infarct extent on T2-weighted MR can probably only be assessed on scans obtained beyond 7 weeks after stroke.     

New Retrievable Coil Anchors: Preliminary In Vivo Experiences in Swine

Purpose To design and test retrievable coil anchors to improve the safety and efficacy of coil embolization.Methods Fifty-two 0.038-inch homemade retrievable stainless steel coils were equipped with one of four different pre-shaped nitinol anchors and tested in 38 pigs. All coils with the anchor were completely retrieved and redeployed 3–18 times (median 7 times) prior to release. Types 1 and 2 anchored coils were acutely deployed in the external iliac arteries (n=10 each), and chronically tested (1 week) in the common carotid arteries (n=6 each). Larger type 1 (n=4), type 3 (n=6), and type 4 (n=4) anchored coils were acutely deployed in the abdominal aorta. The largest type 1 anchors (n=6) were acutely tested in the inferior vena cava.Results All anchored coils were successfully retrieved and repositioned several times. All but two coils formed a compact plug and there was no coil migration except with two mechanically defective type 3 anchors.Conclusion The use of retrievable anchors allowed the coils to be retrieved and repositioned, prevented coil migration, and enabled compact coil configuration.     

The “early filling vein”: Is “early venous filling” in an angiogram really a reliable sign of malignancy?

Summary The case is reported of a 41-year-old man with a meningioma arising from the choroid plexus in the trigonal region of the left lateral ventricle. Carotid angiography revealed that the tumour was surrounded by pathological angiomatous vessels drained by early veins. It is stressed that early venous filling is not a safe sign of malignancy in any tumour.

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Die frühzeitige Venenfüllung: Ist die frühe Vene im Angiogramm tatsächlich ein sicheres Zeichen der Malignität?

Zusammenfassung Fallbeschreibung eines 41-jährigen Patienten mit einem Meningeom, das vom Plexus im Bereich des Trigonum des linken Seitenventrikels ausging. Die Carotisangiographie zeigte, daß der Tumor von pathologischen Gefäßen umgeben war, dabei stellte sich eine frühe Vene dar. Die Untersuchung zeigt, daß diese frühe Vene nicht immer ein sicheres Zeichen der Tumor-Malignität bedeutet.

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L' «Opacification veineuse precoce»: Peut-elle reellement être consideree comme un signe sûr de malignite sur un angiogramme?

Résumé Les auteurs rapportent le cas d'un homme de 41 ans porteur d'un méningiome s'étendant du plexus choroïde à la région trigonale du ventricule latéral gauche. L'angiographie carotidienne démontra que la tumeur était entourée par des vaisseaux angiomateux «pathologiques» drainés par des «veines précoces». Les auteurs insistent sur le fait que l'«opacification veineuse précoce» n'est pas un signe sûr de malignité d'une tumeur.

     

A newly developed intra-operative gamma camera: performance characteristics in a laboratory phantom study

Purpose Radioguided surgery depends on the intra-operative detection of radiolabelled tissues. This is currently accomplished with hand tools capable of providing a tone signal, depending on the proximity and direction of a radioactive source in relation to the probe. The advantages of visual images of radiolabelled tissues are well recognised, but satisfactory means of acquiring such images intra-operatively are not yet available. The goal of this study was to examine the performance of a newly developed intra-operative gamma camera, compact enough to be a hand tool and capable of yielding a visual image of the source field.Methods The study was performed in the laboratory with a phantom consisting of a water bath and small hollow spheres (1–2 cm in internal diameter) filled with ^99mTc (1–5 Ci/cc), placed in different configurations within the bath. For comparison, studies were also performed using a standard intra-operative gamma probe, and others using a standard single-head high-resolution gamma camera.Results Compared with the gamma probe, the intra-operative camera was found to possess a superior ability to distinguish small, deep and weakly localised radioactivity sources from background. By acquiring images from different angles, it allowed a 3D understanding of multiple radioactive sources. It detected cold defects within a hot radiolabelled sphere. It discriminated a weak source located near a much hotter radioactivity source, similar to discrimination with the standard gamma camera, and discerned localised sources against a background of radioactivity.Conclusion It is anticipated that the high imaging potential of the camera tested in this study will offer clinical advantages.     

In vitro and in vivo characterisation of nor-β-CIT: a potential radioligand for visualisation of the serotonin transporter in the brain

Radiolabelled 2-Cabomethoxy-3-(4-iodophenyl)tropane (-CIT) has been used in clinical studies for the imaging of dopamine and serotonin transporters with single-photon emission tomography (SPET). 2-Carbomethoxy-3-(4-iodophenyl)nortropane (nor--CIT) is a des-methyl analogue of -CIT, which in vitro has tenfold higher affinity (IC₅₀=0.36 nM) to the serotonin transporter than -CIT (IC₅₀=4.2 nM). Nor--CIT may thus be a useful radioligand for imaging of the serotonin transporter. In the present study iodine-125 and carbon-11 labelled nor--CIT were prepared for in vitro autoradiographic studies on post-mortem human brain cryosections and for in vivo positron emission tomography (PET) studies in Cynomolgus monkeys. Whole hemisphere autoradiography with [¹²⁵I]nor--CIT demonstrated high binding in the striatum, the thalamus and cortical regions of the human brain. Addition of a high concentration (1 M) of citalopram inhibited binding in the thalamus and the neocortex, but not in the striatum. In PET studies with [¹¹C]nor--CIT there was rapid uptake of radioactivity in the monkey brain (6% of injected dose at 15 min) and high accumulation of radioactivity in the striatum, thalamus and neocortex. Thalamus to cerebellum and cortex to cerebellum ratios were 2.5 and 1.8 at 60 min, respectively. The ratios obtained with [¹¹C]nor--CIT were 20%–40% higher than those previously obtained with [¹¹C]-CIT. Radioactivity in the thalamus and the neocortex but not in the striatum was displaceable with citalopram (5 mg/kg). In conclusion, nor--CIT binds to the serotonin transporter in the primate brain in vitro and in vivo and has potential for PET and SPET imaging of the serotonin transporter in human brain.     

ACL graft can replicate the normal ligament’s tension curve

The anatomical femoral insertion of the normal anterior cruciate ligament (ACL) lies on the deep portion of the lateral wall of the intercondylar fossa. Following the deep bone–cartilage border, it stretches from 11 oclock high in the notch all the way down to its lowest border at 8 oclock. The tension curve of the normal ACL during passive flexion–extension shows a characteristic pattern with two tension peaks, one in full extension and the other in deep flexion. Low tension in mid-flexion is measured between those two peaks. Standard ACL reconstructions use a femoral insertion at 11 oclock, which results in non-physiological tension curves with one peak in full extension only. The hypothesis was that it is possible to reproduce the typical tension curve of the normal ACL by placing the femoral tunnel into the low part of the normal ACL footprint. In a controlled laboratory study, three different femoral tunnel positions at 9, 10 and 11 oclock were tested in four cadaver knees while using the identical standard tibial tunnel each time. The tension curve was measured during passive flexion–extension with a custom-made tension measurement device, using an artificial Dacron graft. The tension curve of grafts in the 9 oclock tunnels showed the characteristic pattern of the normal ACLs tension curve with tension peaks in extension as well as in deep flexion. The tunnels in the 10 and 11 oclock positions failed to reproduce the normal ACLs tension curve with high-tension values in extension only. Clinical relevance: If an ACL graft is placed low within the normal femoral footprint, the physiological tension curve of the normal ACL can be reproduced.     

Imaging of serotonin and dopamine transporters in the living human brain

Alterations in brain serotonin (5-HT) and dopamine (DA) activity are associated with several neuropsychiatric disorders, but until now it has not been possible to simultaneously visualize or quantify the 5-HT and the DA transporter density in the living human brain. In this paper we report on the imaging of 5-HT and DA transporters in 28 healthy controls with single-photon emission tomography using iodine-123 labelled 2-carbomethoxy-3-(4-iodophenyl)tropane ([¹²³I]-CIT) as the tracer. The [¹²³I]-CIT distribution showed the most prominent 5-HT activity in the medial frontal cortex, hypothalamus, midbrain and occipital cortex and the greatest DA activity in the basal ganglia. The specific binding of the 5-HT transporters in the medial frontal cortex was 0.377±0.031 and that of the DA transporters in the basal ganglia, 0.916±0.007. Gjedde-Patlak plots indicated two separate components: the first was assumed to represent 5-HT transporters with a slope of 1.29±0.27 h^–1 and the second, DA transporters with a slope of 0.30±0.04 h^–1. This distinct kinetic pattern and the fact that 5-HT and DA transporters are situated in different parts of the brain provides an opportunity to study in vivo patients suffering from various neuropsychiatric disorders.     

Pulmonary Hypertension Among End-Stage Renal Failure Patients Following Hemodialysis Access Thrombectomy

Purpose: Percutaneous hemodialysis thrombectomy causes subclinical pulmonary emboli without short-term clinical consequence; the long-term effects on the pulmonary arterial vasculature are unknown. We compared the prevalence of pulmonary hypertension between patients who underwent one or more hemodialysis access thrombectomy procedures with controls without prior thrombectomy.Methods: A retrospective case-control study was performed. Cases (n=88) had undergone one or more hemodialysis graft thrombectomy procedures, with subsequent echocardiography during routine investigation of comorbid cardiovascular disease. Cases were compared with controls without end-stage renal disease (ESRD) (n=100, group 1), and controls with ESRD but no prior thrombectomy procedures (n=117, group 2). The presence and velocity of tricuspid regurgitation on echocardiography was used to determine the prevalence and grade of pulmonary hypertension; these were compared between cases and controls using the chi-square test and logistic regression.Results: The prevalence of pulmonary hypertension among cases was 52% (46/88), consisting of mild, moderate and severe in 26% (n=23), 10% (n=9) and 16% (n=14), respectively. Prevalence of pulmonary hypertension among group 1 controls was 26% (26/100), consisting of mild, moderate and severe pulmonary hypertension in 14%, 5% and 7%, respectively. Cases had 2.7 times greater odds of having pulmonary hypertension than group 1 controls (p=0.002). The prevalence of pulmonary hypertension among group 2 controls was 42% (49/117), consisting of mild, moderate and severe pulmonary arterial hypertension in 25% (n=49), 10% (n=12) and 4% (n=5), respectively. Cases were slightly more likely to have pulmonary hypertension than group 2 controls (OR=1.5), although this failed to reach statistical significance (p=0.14).Conclusion: Prior hemodialysis access thrombectomy does not appear to be a risk factor for pulmonary arterial hypertension. Patients with ESRD are more likely to have pulmonary hypertension.     

The “lamellated” skull in β-thalassaemia

The skull in homozygous -thalassaemia may present several abnormalities, such as osteopenia, widening of the diploic space, and a hairon-end appearance. In some cases it presents also a particular stratified appearance caused by a variable number of osseous lamellae, parallel with the inner table. This lamellated skull was observed in 16 out of 150 patients affected by the disease (10.6%). Possible mechanisms are discussed. The lamellar osseous changes could be due to repeated periosteal osteoblastic reactions to the sinusoidal neovascularization associated with marrow hyperplasia in poorly transfused patients.     

Problems with the “dural tail” sign

Prominent enhancement of the dura mater, the dural tail adjacent to a peripherally located mass on gadolinium-enhanced MRI has been described as being characteristic of meningiomas. We present a cerebral glioma showing the classical dural tail.     

Hemorrhage associated with “bone crisis” in Gaucher's disease identified by magnetic resonance imaging

Children suffering from Gaucher's disease were examined by magnetic resonance imaging (MRI) during a characteristic episode of bone crisis. An unexpectedly high intramedullary as well as subperiosteal signal was observed on both the T1 and T2-weighted sequences in 5 patients, suggesting a subacute hemorrhage or hematoma. It is conceivable that such a painful hemorrhage is an important component of the bone crisis phenomenon. Furthermore, in these cases this is a specific sign which may enable differentiation of bone crises from other types of bone pain associated with Gaucher's disease.